Parents contacting the health care telephone enquiry agency, the primary care emergency unit, the paediatric emergency unit, all at the Umeå University Hospital or the well-baby care centres (BVC) in Umeå for advice on their children's gastroenteritis will be informed that they may participate in the present study and they will be given contact information to the research nurse for this activity. A home visit by study personnel will then be done for evaluation of eligibility, information, collection of informed consent and delivery of study product.